How to use COLOR in applications
You can find a list of all the pre-named colors available, by typing the
following command at the main prompt:
more /usr/lib/X11/rgb.txt
On the Suns use:
more /usr/openwin/lib/rgb.txt
This lists the names of available colors and their corresponding rgb
values. Here's an excerpt from the X man page, explaining how rgb works:
----------------------------------------
COLOR NAMES
Most applications provide ways of tailoring (usually through resources
or command line arguments) the colors of various elements in the text
and graphics they display. Although black and white displays don't pro-
vide much of a choice, color displays frequently allow anywhere between
16 and 16 million different colors.
Colors are usually specified by their commonly-used names (for example,
red, white, or medium slate blue). The server translates these names
into appropriate screen colors using a color database that can usually
be found in /usr/lib/X11/rgb.txt. Color names are case-insensitive,
meaning that red, Red, and RED all refer to the same color.
Many applications also accept color specifications of the following
form:
#rgb
#rrggbb
#rrrgggbbb
#rrrrggggbbbb
where r, g, and b are hexadecimal numbers indicating how much red,
green, and blue should be displayed (zero being none and ffff being on
full). Each field in the specification must have the same number of
digits (e.g., #rrgb or #gbb are not allowed). Fields that have fewer
than four digits (e.g. #rgb) are padded out with zero's following each
digit (e.g. #r000g000b000). The eight primary colors can be represented
as:
black #000000000000 (no color at all)
red #ffff00000000
green #0000ffff0000
blue #00000000ffff
yellow #ffffffff0000 (full red and green, no blue)
magenta #ffff0000ffff
cyan #0000ffffffff
white #ffffffffffff (full red, green, and blue)
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Colors produced by rgb values may vary across monitors. There are,
however, ways of quickly playing around with rgb values and seeing their
affect. One way is to type this at the main prompt:
add graphics
xv /usr/athena/lib/X11/bitmaps/mensetmanus &
(you can specify any bitmap there instead of the mensetmanus one)
When the picture comes up, hit 'e' in the window. A big window with lots
of buttons will come up, including three dials of particular importance,
labelled Red, Green, and Blue. You can adjust these values by clicking on
the dial, and the change will be reflected in the background of the bitmap
shown. To change the color of other regions (such as the foreground),
just click on the region you wish to edit in the picture with the left
mouse button.
To specify colors for X applications, you can usually do:
program -fg "foreground color" -bg "background color"
Some examples of programs you can do this with are xterm, emacs, ez, and
matlab. If the name of the color has spaces in it, you should surround it
with double quotes like above. You can also use an rgb specification
instead of a color name. For example, the same thing happens if you type
either of these two commands:
emacs -fg yellow -bg magenta
or
emacs -fg "#ffffffff0000" -bg "#ffff0000ffff"
(Last updated Aug 12, 1997)
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